I read Justice League Dark....this might be a good dropping off point though.
Still, I'd probably be able to follow along since a good part of the story is in JLD.
However, since it spins out of Villains, which I'm not following, I may be lost from the start. TBD.
Guess this means JLD will be one of the few "Dark Line" books from the nu52 to hit a #30 and beyond.